The need for emergency shutdown of an internal combustion engine may arise in a variety of situations. Fugitive fueling is one such situation. As used herein, the term “fugitive fueling” means the phenomenon in which an engine receives fuel in excess of that which a fuel controller intends to deliver, either by injectors or by another fuel delivery device. Fugitive fueling may occur in a variety of situations. For example, if an engine is operated in a hydrocarbon-contaminated atmosphere, such as could occur in the event of a spill at a petroleum transfer terminal or a recycling facility, sufficient unwanted, or fugitive, hydrocarbon may be inducted by the air system of an engine to cause overspeed and severe engine damage. A mishap such as a vehicular accident or train wreck may create a fugitive fueling situation, too.
Another type of fugitive fueling may occur due to a leak in an engine lubrication system. Such a leak may occur in a turbocharger or other component connected with the engine's air inlet system. Those skilled in the art will appreciate that engines, particularly diesel engines, are capable of operating quite well on lubricating oil, including lubricating oil aspirated into the engine's cylinders as a result of leaking turbocharger seals or even worn valve guides. Yet another type of fugitive fueling may occur if a fuel system injector is severely impaired such that the injector either flows more than it is intended to flow, or simply leaks. These sorts of impairment will most likely occur with an unthrottled engine having fuel injection, but could occur with a carbureted engine as well.
U.S. Pat. Nos. 6,429,540 and 6,522,439, which are assigned to the assignee of the present invention, address methods for responding to an engine overspeed condition resulting from ingestion of lube oil into an engine's cylinders.
Emergency shutdown may be indicated for reasons other than fugitive fueling. For example, engine overspeeding due to a loss of governor control, or excessive vibration resulting from mechanical faults, or overtemperature, or loss of oil pressure due to leaks or oil pump impairment, all militate in favor of emergency shutdown.
A need therefore exists for a system employing a direct-coupled rotating electrical machine to rapidly stop an engine if an emergency condition occurs.